Tube calipering device



March 7, 1961 D E, STQLLE ET AL 2,973,583

TUBE CALIPERING DEVICE Inventors B J florney .D 0 .D u w E n m e &\ E E6N t w am 2 \l .14, 6 4 6 \l fiZ /fl! w o 8 H; E z iZ \W Q v Q m. p a rlM m 3 n Donald E. Srolle Newbold 0. Cross FlG.-IA

Filed Sept. 12, 1958 March 7, 1961 D. E. STOLLE ETAL 2,973,533

TUBE CALIPERING DEVICE Filed Sept. 12, 1958 2 Sheets-Sheet 2 FIG-3Donald E. Srolle N b Cross Inventors Y Attorney TUBE CALIPERING DEVICEDonald E. Stolle, White Plains, N.Y., and Newhold 0. Cross, BerkeleyHeights, N..l.; said Stolle assignor to Standard-Vacuum Oil Company, acorporation of Delaware, and said Cross assignor to Esso Research andEngineering Company, a corporation of Delaware 'Filed Sept. 12, 1958,Ser. No. 760,797

2 Claims. (Cl. 33-178) The present invention relates to animproved-device for calipering the internal surface of tubular conduits.The invention particularly relates to a device for cating and measuringsurface irregularities such as are produced by erosion, corrosion, andespecially that resulting from mechanical damage of the internal wallsof conduit tubes such as employed in heat exchangers, tubular reactors,furnaces and the like.

Such tubes are usually of small diameter, and in addition to damageresulting from normal service, may develop internal accumulations ofcarbonaceous deposit. In reactor tubes, where the tubes are packed withsolid catalysts, the catalyst particles may become so coated withreaction products as to completely block the tube. In any event, thedeposits and other obstructions usually require removal by drilling andwire brushing. This must be done by means of a drill head or brushmounted on a rotatable shaft which can be extended for the length 7 ofthe tube. Due to the length of shaft required, it tends to develop awhipping motion, causing the drill head or brush to deviate from a pathconcentric with the tube, and thereby to strike against and damage thetube inner surface. On occasion such damage, termed gun cuts, may besevere enough to render a tube unsafe.

It is an object of the present invention to provide means whereby thelocation and depth of such gun cuts and other irregularities in theinner surface of tubular conduits may be determined. It is a particularobject of the invention to provide such a means, wherein determinationis accomplished by a unitized feeler and transmission assembly which isquickly and easily replaceable in the main body of the caliper unit. Afurther object of the invention is to provide a calipering device,employing an electrical indicating system, and suitable for use in thepresence of potentially explosive atmospheres.

The invention and its objects may be more fully understood from thefollowing description, when it is read in conjunction with theaccompanying drawings, where- 1n:

Figs. 1A and 1B illustrate opposite end portions of the device arrangedto show their assembled relationship and disposition in a tubularconduit. Each figure provides a view in longitudinal sectiondiametrically of the device and conduit, with a portion of the deviceshown in elevation by Fig. 1A;

Fig. 2 is a view in cross section, taken along the line II--II of Fig.1B;

Fig. 3 is an exploded view of the feeler and transmission mechanismaccording to the present invention; and

Fig. 4 is a perspective view of an instrument case adapted to containmeans for exhibiting electrically the irregularities encountered bypassage of the device through a tubular conduit.

Referring now to the apparatus components as illustrated by Figs. 1A,1B, 2, and 3, the numeral 1 desiginserts for the head and tail portions201 and 20.

2,973,583 Patented Mar. 7, 1961 nates a tubular conduit, such as heatexchanger, or a reactor tube. The numeral 1a designates a pit in theinternal surface of the tube, and the numeral 2, a caliper deviceaccording to the present invention, wherein the portion designated 2a inFig. 1A is the head portion of the device, the portion 2b in Fig. 1B isthe central portion and the portion 2c is the tail portion. In Fig. 1Athe head portion 2a is shown partly in longitudinal section and partlyin elevation, while in Fig. 1B, the central portion and tail portion areillustrated in longi tudinal section. A part of the head portion 2a asshown in Fig. 1A, including the externally threaded coupling end 3, alsois shown in Fig. 1B. As shown, the end 3 of portion 2a is adapted forthreaded engagement in the internally threaded coupling end 4 of thecentral portion 2b, as shown in Fig. 1B.

The head and tail portions 2a and 2c separated by central portion 2bform a tubular housing adapted to contain a caliper mechanism, includingmeans for centering the housing in a conduit tube. Caps 5 and 6 provideend closures for the head and tail portions respectively of the housing.

At each end of the housing, the respective portions 2a and 2c define acircumferential series of longitudinally extending slots such as theslots 7 in portion 2a, and the slots 8 in portion 20. These slots 7 and8 provide for extension therethrough of a corresponding series ofcentering wheels or rollers 9 and 10, adapted to engage the innersurface of the conduit 1, in the manner shown, whereby to center thehousing in the conduit.

The wheels 9 and 10 are parts of an identical pair of The insert for thehead portion includes inner and outer cylindrical plug portions 11 and12, respectively, each having obverse and reverse surface portions 11aand 11b, and 1242' and 12b. The plug portions 11 and 12 are joined andspaced in coaxial relation by means of a tube 13 which is disposed inparallel eccentric relation to the axis common to each plug portion. Thetube 13 is frictionally engaged at each end. in passageways 14 and 15defined in and opening through the obverse and reverse surfaces of therespective plug portions. A series of paired spring supports 16 aremounted in vertical receiving recesses or passageways 17 defined in theplug portion 11, each pair of spring supports being adapted to provide amount for the wheels 9 audit), and to extend the wheel outwardly andradially of the insert. The pairs of recesses 17 are disposed in spacedrelation peripherally of the plug portion obverse surface 11a, so as tocorrespond with the spacing of the slots 7, whereby the' wheels mayextend therethrough. The insert, .in-

eluding plug portions 11 and I2, is adapted for slidable insertion intothe housing head end portion 2a, and is retained therein as by means ofset screws 18 and 19.

When thus inserted, and the cap 5 applied, a chamber 20 is formedbetween the cap and the obverse surface 12a of the plug 12. The reversesurface 12b defines a series of recesses 21 which are arranged so as tocorrespond with the slots 7 in the housing of head portion 2a, andadapted to serve as wheel guides for the wheels 9.

The insert provided for the opposite end of the housing, and adapted forslidable insertion in the tail end portion 20, is shown in Fig. 1B. Asnoted, this insert is identical with that for the head end portion 2a.In Fig. 1B, the several parts of the tail end insert are designated bynumerals corresponding to those for the parts of the head end insertshown in Fig. 1A, except that in Fig. 1B such numerals are all in theseries.

In addition to the slots 8 defined in the wall of the tail portion 20,the threaded coupling end also defines a second circumferential seriesof slots which extend longitudinally through the central portion 2b;these slots are designated in Figs. 18 and Fig. 2 by the numeral 30.Preferably the slots 36 are arranged as diametrically opposed pairs. Asshown in Fig.2, three such pairs are provided.

The coupling end of the central housing portion 212 also is adapted toreceive the feeler and signal transmission unit including a cylindricalplug 31 having obverse and reverse surface portions 31a and 31b, whichplug is insertable in the central portion for a sliding fit therein. Aset screw, not shown, is provided through the wall the central portion2b to retain the plug. In the assembled housing, the plug 31 divides thehousing as a partition, to form a chamber 32 between the plug portionsurface 11b and the reverse surface portion 3112. This chamber 32communicates with the chamber '26, by way of the tube 13.

The plug 31 is provided with a concentric passageway 33 opening at theends thereof through the obverse and reverse surface portions of theplug, 31a and 31b, respectively. That portion of the passageway whichopens through the obverse surface portion 31a is enlarged to provide anoutwardly facing internal annular shoulder 34. The enlarged portion ofthe passageway 33 is designated in the drawings by the numeral 33a. Thepassageway is provided to receive a plunger element having a shaft 35and a head portion 36, the shaft and head portions together beingslightly longer than the passageway, with the shaft disposed for slidingreciprocal movement in the passageway and the head portion 36 similarlydisposed in the enlarged portion 33a. A helical expansion spring 37 isdisposed between the head portion 36 and the annular shoulder 34, beingadapted to bias the plunger in the direction of the plug obverse surfaceportion 31a.

The plug 31 defines a series of slotted portions 38 disposed in spacedrelation circumferentially of the plug. The spacing of these slottedportions conforms to the spacing of the slots 30 in the housing portion2b of Fig. lB. Each slot opens through the obverse and reverse surfaceportions 31a and 31b and extends inwardly into spaced relation to thewall of the passageway 33 adjacent the reverse surface portion, andopens through the wall of the enlarged passageway portion 33a. Betweenslotted portions the peripheral edge of the obverse surface portion ischamfered as at 39 providing a series of paired ear portions 40 each ofwhich is drilled to receive a retainer pin 41. In addition, the plug 31defines a series of recesses 42 of substantially circular cross section,each having an axis centered on the center line of a slotted portion 38and extended inwardly toward the axis of the plug 31 into spacedrelation to the passageway 33 defined therein. Each such recess providesa receptacle for an expansion spring such as designated in Figure 1B bythe numeral 43. A second passageway 44 is defined in the plug 31eccentrically thereof so as to open through the respective surfaceportions thereof.

Each of the slots 38 is adapted to receive a feeler element 4S pivotallymounted therein by means of a pin 41. Each feeler element is formed andmounted so as to provide a finger portion 45a adapted for extension froma slot under pressure of spring 43 against the inner edge of the feelerand a plunger-head, bearing lip 45b extending inwardly from the feelerinner edge, and adapted to engage the outer surface of the plungncr headportion 36. The springs 43 and 37 are compressed so that the pressureexerted by any one of the springs 43 will exceed the pressure exerted bythe spring 37. When the plug 31 is inserted in the slotted end of thecentral housing portion 2b, the fingers 45a are adapted for extensionthrough the respective slots 30 under pressure of the springs 43. Asleeve 52 on the central housing portion 2b is provided for reciprocalmovement thereon to engage the feeler fingers 45a, whereby to retainthem in at least a partly retracted position.

The reverse surface portion 31b of plug 31 provides a mounting surfacefor a support member 61 mounted thereon, as by means of screws 61a, inperpendicular relation to the surface 31b. The outer end of the support61 is adapted to receive a rotatable shaft 62 on which is a pinion 63.The support 61 is also provided rotatably to receive a shaft 64 carryinga sector gear 65 in meshing relation to the pinion 63. The shaft 64 alsocarries in fixed relation thereto a crank arm 66. A link 68 is pivotallyconnected to the crank arm 66 and shaft 35 respectively substantially asshown. The relationship of these parts is particularly illustrated bythe exploded view of Figure 3. In this view the support for the outerends of the shafts 62 and 64 have been omitted for better illustrationof the parts themselves. In Figure 18, however, the numeral 67designates a plate support member mounted in spaced relation to thesupport 61, and secured thereto by means such as spacer bolt 67a,whereby to engage and support the outer ends of the shafts 62 and 64.The plate support 67 also provides a mount for a voltage dividerresistance element 71 having wire connections 71a and 71b, respectively.A voltage divider slider element 72 is mounted on the outer end of theshaft 62 for arcuate movement thereby over resistance element 71. Theslider 72 also is provided with a wire connection 72a.

The wire connections 71a, 71b, and 72a are extended from their voltagedivider connections through the passageway 44 and tube 113 toward thetail end of the housing. The three connections form part of a 3-wireconductor 81 extended through a passageway 6a in the cap 6. A coupling6b provides means whereby the conductor 81 is fixedly associated withthe cap and thereby with the housing.

Referring now to Figure 4, the numeral 90 designates an instrument casehaving an internal partition 92 dividing the case into chamber portions90a and 90b. The partition 92 defines a series of passageways 92acommunicating between the respective chamber portions. The case 96provides a housing for a voltmeter 82, battery 83, and resistanceelements 84, 85, and 86, all connected in the voltage divider circuitthrough a switch 87. The resistance element 86, as indicated, is avariable resistor.

Although not shown in Figure 4, the case would be provided with a pairof cover plates adapted to be mounted on case rim portions 91 andengaged therewith in substantially sealed relation by means such as studbolts 91a. The wire connections 71a, 71b, and 72a are brought into thechamber portion 90a by means of the conductor 81 which is extendedthrough a coupling device, designated by the numeral 93, which isadapted to hold the conductor in fixed and fluid tight relation to thecase. Preferably the voltmeter 82, switch 87, and the variable resistorelement 86 will be mounted on the cover plate provided for the chamber90a whereby they may be available for observation or actuation. Theconnections to these elements and the remainder of the wiring circuitmay be loosely disposed within the chamber. The threewire conductorcable 81 may be provided with suitably spaced marks indicatingprogressively from a line adjacent cap 6 the total distance from thefeeler elements 45 to and point along the cable. Preferably such markingwill be in feet and inches.

In the voltage divider circuit as shown, the resistor 84 is disposed inseries with the voltage divider resistance to simulate infiniteresistance whereby to decrease current consumption. The variableresistor 86 is shunted across the internal resistance of the voltmeter82 whereby to regulate the sensitivity thereof, to permit initialadjustment of the meter to a zero reading, and to compensate for feelerfinger wear.

In operation, the chamber 90b is first filled with Dry Ice as is alsothe chamber 29 in the 'housing 2. This is done to provide anon-explosive atmosphere in the areas surrounding electrical connectionssuch as those existing awaees in the chamber 99a and in the chamber 32.Transformation of the carbon dioxide from its solid form to its gaseousform produces a pressure which is transmitted from the chamber 90b tothe chamber 90a by way of the passageways 92a, and from the chamber 20to the chamher 32 by way of the passageway provided by means of the tube13. in each instance an atmosphere of gaseous carbon dioxide is createdin the vicinity of such electrical connections, which accomplishesexclusion of any combustible or explosive atmosphere existing within thetube 1, or adjacent areas. When thus prepared for use, the feelerelements 45 are at least partly retracted by moving the sleeve 52 towardthe head end of the assembled housing whereby to engage the fingers 45aforcing them into the slots 38 against the pressure exerted by thesprings 43. Retraction of the feeler elements permits the plunger headand shaft portions 36 and 35, respectively, to move outwardly toward theobverse portion surface 31a of the plug 31. In doing so, the crank 66moves the sector gear 65 arcuately and in turn moves the slider 72through the gear #33 and shaft 62. The slider 72 is moved toward theterminal connection of the wire connector 71b to the voltage dividerresistor element 71. The housing may then be inserted in the tube to becalipered by depressing the wheel elements S and against the pressure oftheir respective spring supports. In any suitable fashion the housing isthen passed entirely through the tube to the end opposite that of itsinsertion. The sleeve is then retracted to permit extension of thefingers. The housing is then drawn toward the insertion end of the tubewhile compressing feeler elements as required to permit re-insertion ofthe device in the opposite end of the tube. At this point, with thefingers 45a in engagement with the inner surface of the tube, thevariable resistor 86 is adjusted to provide a zero reading on the meter.The housing is then drawn through the tube by means of the conductor 81.If any gun cuts or other irregularities are present, such as the pit 1:;shown in the drawing, one or more of the fingers will be extended to adegree greater than permitted by a regular tube surface. When thusextended, any one or more of the bearing lip portions 4517 will pressagainst the plunger head portion 36 moving the shaft outwardly from thepassage 33. Through the link 68 and crank arm 65, the sector gear 65,through pinion 63, translates this straight line motion into arcuatemotion of the slider 72 on the resistor 71 thereby changing the voltageimpressed on the meter 32. This change in voltage is readily translatedinto an indication of the depth of the irregularity encountered by thefinger portions 45a. If the irregularity encountered by two or morefinger portions is of varying depth, then the deepest portionencountered by any finger is that which will be shown by the meter. Themeter reading may either be compared with a predetermined scale ofreadings indicating various pit or other irregularity depths, orpreferably the meter may be calibrated and scaled to permit a directdepth reading in fractional inches. As previously stated, the housing issubstantially centered in the tube being measured by means of the springmounted wheels 9' and 10. The exact location of any irregularityindicated in this manner with reference to either end of the tube willbe provided if suitably spaced marks or linear indicia are carried onthe conductor cable 81.

What is claimed is:

1. A calipering device for measuring irregularities in the internaldiameter of a tubular conduit, comprising a tubular housing adapted tofit said conduit freely, said housing including head, central, and tailsections, said head and tail sections having outer ends forming oppositeends of said housing, the head and tail section each containing a seriesof slots opening through said ends to extend longitudinally of saidsections and disposed in spaced relation circumferentially thereof, apartition insert disposed intermediate the ends and within each of thehead and tail sections, a removable cap for each outer end, the headsection cap and the partition insert for this section defining a firstchamber adapted to be charged with an inert gas forming materialincluding solid carbon dioxide, an insert in said central sectionincluding a cylindrical solid body portion having obverse and reversesurface portions, said body portion coaxially defining a passagewayopening through said surface portions and enlarged inwardly from saidobverse surface portion to form an internal annular shoulder, a plungerelement including substantially integral shaft and head portionsdisposed for reciprocal movement longitudinally of said passageway withsaid head disposed and slidably fitted in the passageway enlargedportion, said body portion containing a series of slots extendinglongitudinally thereof and in circumferentially spaced relation, thenumber and spacing of said slots corresponding to slots in the casing ofsaid central section, said body portion slots opening through saidobverse and reverse surface portions and through the wall of theenlarged passageway portion, a series of feeler elements pivotallymounted in said body portion slots, spring means biasing said feelerelements to extend them outwardly at one end through said slots in thehousing of the central section and inwardly at the other end to engagethe plunger head portion, a voltage divider means mounted on the reversesurface of said body portion, including a resistor and a slider movablethereover from end to end, means to move said slider including a linkconnection to the plunger shaft portion, the body portion reversesurface being disposed in spaced relation to the head section partitioninsert and defining therewith a chamber in said central section, saidchamber adapted to contain said voltage divider means and mounttherefor, with said central and tail sections in threaded engagement, aconduit communcating between the head section chamber and the centralsection chamber, meter means adapted to indicate the position of saidslider and thereby the position of maximum extension of at least one ofsaid feeler elements, conductor means for connecting said voltagedivider and said meter means, including a conductor cable adapted tosupport and to draw said calipering device through a conduit to becalipered, and means to support and maintain said device insubstantially coaxial reciprocally movable relation to said conduit.

2. A caliper device according to claim 1, wherein each of said partitioninserts comprises a pair of cylindrical partition elements disposed inparallel, coaxial relation and in spaced relation longitudinally oftheir common axis, and said conduit communicating between said headsection chamber and said central section chamber is in radiallydisplaced parallel relation to said axis, said conduit being secured atthe respective ends thereof in corresponding passageways defined in andopening through said respective partition elements.

References Cited in the file of this patent UNITED STATES PATENTS2,150,070 Kregecz Mar. 7, 1939 2,324,865 Milligan July 20, 19432,518,663 Chaney et al. Aug. 15, 1950

